But beyond a brief discussion in the House Transportation Committee, the recent debate in Lansing has not included a substantive look at toll roads.

That's because some state leaders, including Michigan Gov. Rick Snyder, don't think toll roads are a realistic solution to fix Michigan's crumbling infrastructure.

"We made a decision a long time ago, back in the Eisenhower days when we did the Interstate system, that we weren't going to do toll roads," Snyder said Wednesday night during a public forum in Novi.

The federal government paid a substantial portion of construction costs on many Michigan highways and generally prohibits the imposition of tolls on those roads. If Michigan wanted to simply convert an existing freeway into a toll road, it would have to repay the federal government's full investment.

"It's not something that's financially viable for any existing road," Snyder said, "because that's decades of involvement and all those dollars. We can't afford to essentially buy back that road to make it a toll road."

Federal law does allow states to impose tolls on federal-aid highways in certain circumstances. For instance, Michigan could add new lanes onto an existing highway and seek approval to fund the project via tolls. The state could also reconstruct a non-Interstate highway or build a new highway from scratch and make it a toll road.

Such projects could be "part of a discussion," Snyder said, but he noted that Michigan doesn't necessarily need new highways, it just needs to maintain existing ones.

A number of prominent toll roads in the region were built prior to the Interstate system and do not face restrictions tied to federal funding. The Ohio Turnpike, for instance, was completed in 1955, one year before the Federal Highway Act of 1956.

A 2008 task force headed by Michigan Chamber of Commerce President Rich Studley suggested the state should explore the possibility of toll roads. But the task force also recommended increasing registration fees, eliminating registration discounts and adjusting motor fuel taxes.

Snyder, who is urging the Legislature to increase road funding by more than $1 billion a year, had originally proposed raising that revenue through a combination of gasoline taxes and registration fees. But that idea failed to win over many lawmakers.

Legislative leaders have been meeting with Snyder this summer in hopes of finding a long-term solution, and there have been talks of an alternative approach that would rely on voter approval for a sales tax increase of between 1 and 2 percent.

Snyder said he does not have an official position on that idea, which a handful of lawmakers on both sides of the aisle have already criticized. A legislative solution to Michigan's long-term road funding problem may remain a longshot.

Jonathan Oosting is a Capitol reporter for MLive Media Group. Email him, find him on Google+ or follow him on Twitter.